New York City's subway system hustles thousands of people through its tunnels on a daily basis. But deep in the labyrinthine network of tracks and tunnels, exists a much slower-moving people, who call this dark outpost home.

In his 2000 documentary Dark Days, Marc Singer follows a group of homeless New Yorkers living in one particular underground tunnel. The characters themselves and their stories are often quite compelling, but what's maybe most fascinating is the elaborate and technologically skillful livable homes they've built down below—complete with jury rigged electricity to power their TVs and radios and lightbulbs, and Rube Goldberg machine security systems comprised of pots and pans and twine and pencils.

At times, the film can be difficult to watch. But that's only a testament to Singer's ability to find a story and make us care, when we might otherwise just pass these people by. Living in the city, I think about this movie all the time. You should definitely check it out. [Netflix]